The Ice Knit is different because it reacts to the external temperature.

A Stone Island spokesman said: “Garments are created with a double knit construction: the outer face is made in an exclusive thermo-sensitive yarn that drastically changes colour when exposed to cold, while the inner one is in pure wool.”

It means there are no awkward sweat-patch shapes in the contrasting colours, although it is still possible to make hand prints.

As well as the sweater, Stone Island’s AW 17/18 range includes a zipped hooded-cardigan and a beanie hat.(Stone Island/PA)

Stone Island has a history of applying innovative design and tech to its fashions.

While the Ice Knit is the first thermo-sensitive sweater, the company’s first such piece was the Ice Jacket which launched in 1989 and has evolved in different colours and styles since then.